Electric insulator



(No Model.) I'. BAIN. ELECTRIC INSULATOR.

No. 443,187. Patented Dec. 2 3, 1890.

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UNITED STATES PATENT OFFICE.

FORE BAIN, OF CHICAGO, ILLINOIS.

ELECTRIC INSULATOR.

SPC'IFICATON forming part of Letters Patent No. 443,18*?, dated December 23, 1890.

Application filed March 25,1890. Serial No. 345,287. (No model.)

To all whom, it may concern:

Be it known that I, FORE BAIN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Improvement in Electric Insulators, of which the following is a specification.

My invention relates to the class of insulators employed most commonly with the poles io on which overhead electric wires are strung, being usuallycomposed of glass or porcelain, and involving, as the general construction, a head cir-cum ferentially grooved to adapt it to receive the binding-Wire, andhaving an internal-threaded socket to receive the supporting-pin and a petticoat7 portion.

My improvement relates, more particularly, to the petticoat portion referred to, my obj ect being to so construct it as to prevent the forzo mation of a continuous film of moisture from the Wire to the pin, affording a conductor that would ground the circuit.

I accomplish my object by forming the insulator circumferentially with sharp projecting lines, ridges, or corrugations.

The accompanying drawing shows an insulator of my improved construction, in broken elevation, on its supporting-pin.

A is the insulator, formed of glass, porcelain, or other suitable insulating material, and provided with the usual head portion r, having the circumferential groove n for the binder o, with the internally-threaded socket q for the pin p, and with the petticoat portion B.

Vhen the insulator A, as is commonly the case in its use, is exposed, unless means he provided toprevent, a continuous film of moisture may form upon it, and thus aiord a conductor from the Wire 0 or the hinder o along 4o the outer and inner sides of the petticoat to the pin, tending to ground the circuit, and thus lower the insulating resistance. I prevent this by forming ci rcumferentially around both the outer and inner surfaces of the petticoat B a series of ridges m or corrugations, which should be sharp and separate, as illustrated. These break the continuity of the film, and thus prevent the formation of such a conductor as would cause the grounding of 5o the circuit.

What I claim as new, and desire to secure by Letters Patent, is-

An insulator A, comprising, in combination, a head portion r and a petticoat portion 5 5 B, with an intermediate groove n for the binder o', the petticoat portion having formed upon its outer and inner surfaces a continuous series of separate circumferential sharp ridges m, substantially as and for the pur- 6o pose set forth.

nonne BAIN. 

